The combination of Synergex T Plus, Synergex T & MDEA allows formulation of formaldehyde-free and boron-free metalworking fluids.

• Synergex T is a lower VOC (< 25% volatile by ASTM E 1868) amine additive for metalworking fluids.
• Both Synergex T Plus and Synergex T are tertiary amines.
• Both Synergex T Plus and Synergex T are pure products.

MDEA (Methyldiethanolamine) is an ideal lower odor, lower VOC, economically priced alkanolamine that can be used to bring the pH of the operating fluid up to 9. Use MDEA instead of MEA, DEA and TEA to help improve performance at a reasonable cost.

Concentrates formulated with 3% Synergex T Plus and either 10% phenoxyethanol or 10% phenoxypropanol type biocontrol agent are recommended.

Concentrates formulated with 5% Synergex T and either 10% phenoxyethanol or 10% phenoxypropanol type biocontrol agent are recommended.

The following concentrate formula represents a good starting point for fully synthetic fluids based on SynergexTM T Plus & MDEA.

• The biocontrol system can be changed from phenoxyethanol to 50ppm BIT (diluted fluid) – use water to adjust volumes. The phenoxyethanol biocontrol system can be swapped out for BIT (50 ppm effective concentration operating fluid; adjust concentrate volume with water).
• Polyalkylene glycol (Polartech SGL) is formulated specifically for use in high performance fully synthetic metalworking fluids.

The above concentrate can be diluted 20/1 to provide the operating fluid. The addition of preferred corrosion inhibiting additive(s) and/or packages is recommended. Note that tertiary diethanolamines like Synergex T and Synergex T Plus are known to provide longer life in fully synthetic metalworking fluids (see; Golec, K.; Hill, E.C.; Kazemi, P.; Skold, R. O.; Tribology International 1989, 22(6), 375 – 382.)

Formulating with Synergex™

Synergex™ products can extend coolant life and improve the performance of most water-based metalworking fluids.

Eastman's Synergex^™ family of multi-functional amine additives can be used in combination with other amines or used by themselves in a concentrate, used tank side, or used to make corrosion inhibiting salts and amides. Synergex^™ products can extend coolant life and improve the performance of most water-based metalworking fluids.

If this Synergex™ salt is used to make up 24% of the synthetic or semi-synthetic formulation, then the concentration of Synergex™ in the final concentrate will be 6%, ideal for optimizing all the benefits of a synergistic amine. The above Synergex™ salt will be replacing rust inhibitors that typically contain only 5% to 25% water so adjust your formula accordingly.

Recommended semi-synthetic formula

The Semi-Synthetic formula with a Synergex™ salt rust inhibitor was compared to a Semi-Synthetic formula made from DCHA and another Semi-Synthetic formula with a commercial TEA/Primary amine based Boramide. All three formulas showed no rust in distilled water at a 5% dilution in a typical cast iron chip on filter paper rust test. The aluminum leaching results were very favorable to Synergex™ containing semi-synthetics. Also in the cobalt leach, the Synergex™ containing synthetics did very well. Lastly, the Cast Iron Chip rust testing showed that at the concentrations necessary for long coolant life (5% dilution), there is no trace of rust.

Synergex™ neutralizing amine as rust inhibitors

Synergex™ neutralizing amine additives¹ have anti-rust properties superior to those of commodity ethanolamines such as monoethanolamine (MEA) & triethanolamine (TEA), and they will tolerate higher carboxylate contents (with less water) when used in a water soluble metalworking fluid rust inhibitor concentrate. One such formula has been used with self emulsifying esters (SEE's), reverse block polymers and tramp oil rejecting emulsifiers in semisynthetic metalworking fluid concentrates.

Table 2 The formulas for the rust inhibitors

Aqualox® is a registered trademark of the Lubrizol Corporation.

Corfree® is a registered trademark of INVISTA S.a.r.l.

Emerox® is a registered trademark of Emery Oleochemicals GMBH.

Formula 3 Synergex/MIPA/Corfree® M1 is the same as the rust inhibitor with Synergex/MIPA/Corfree® M1 from table 1

Because only formula #5 showed rust, we conclude that Synergex/MIPA is a better amine combination than TEA/MEA for preventing rust. At 15% by weight in the coolant concentrate, the amount TEA at 6% dilution of the metalworking fluid is 9,000 ppm. The contribution of MIPA and Synergex from 15% of the rust inhibitor is 2,722 ppm, sufficient for long life activity. The rust testing was done at 3% just to stress the fluid otherwise there would be no rust at all with the fresh dilutions. Because these formulas represent synthetic metalworking fluids, there was no oil in any of the finished fluid formulas. Using Synergex and MIPA to make up the rust inhibitor instead of the more common use of TEA & MEA, allows for not only a more rust resistant formula but also one that has long life properties.

Synergex™ LA is an ideal hydrophobic amine for metalworking

As the following table illustrates, Synergex LA provides faster wetting time on aluminium when compared to many other amines. A balanced combination of Synergex LA with MIPA can provide for greatly extended fluid life (see formula below).